At which point I would have to come out of pocket ($18k additional for $80k total renovation) to succeed in renovating the property to its full appraisal potential. 

Will you need to put additional time and money into this to make it a viable rental?

There is going to be a special assessment soon of about 2,000 + 2 years of an additional 150/month.I can't deal with tenants calling me constantly with every little thing that is wrong (my pipes tend to clog) so rental would be contingent on tenant handling these things on their own.If I do sell, I would put the money in a mutual fund.What do you think?

@Ryley White the $10,000 would be in addition to the purchasing cost. 

One is a 3 bedroom 2 bath built in 1953 and the other is a 4 bedroom 2.5 bath built in 2007  (built as addition with full permits).

In addition, unlike the STRs, there has been little significant push for rent control.  

If you're going to flip it why refi, you're going to have to pay additional fees on closing costs etc. 

This would prevent any personal use of property owned by your Solo 401k.

If you were ok with taking on additional debt (loans your tenants would pay down for you over time), you could potentially leverage that 475k into 10 or more cash flow properties (though there are limits on how many loans you can carry at once).Of course, there's always a middle ground too: sell the condo, use some of the money to increase your DP on the new house and use the rest for investing.

In addition to the links that Marlon suggested, I’d also recommend going to Meetup.com and looking in the “Career and Business” category.